Recipes are commonly used to create culinary combinations of food or drink. As used herein, culinary combinations will include creations of mixology and of cooking. The foundations of all recipes are culinary ratios. A culinary ratio is a fixed proportion of one or more ingredients of a recipe relative to another. These ratios are fundamental to the crafts of cooking and mixology. Understanding that recipes are ratios allow one to consistently scale or adjust recipes and to fix a recipe if one makes a mistake and adds too much of a certain ingredient.
When preparing food or drinks, it is best to use weight rather than volume for measuring most ingredients. Properties of a culinary combination are more closely dependent on the ratio of the weights or masses of ingredients, than on their volumes. For a culinary combination to have the desired properties, the ratios of the masses or weights of the ingredients must be achieved. Volumetric measurements may be convenient approximations for weight, but it the weight or mass of the ingredients that is desired. Measuring by volume can introduce inaccuracies. The volume of a certain mass of a material can change based on environmental conditions such as temperature, pressure and humidity. Because of this, powder ingredients like flour are in particular more accurately measured by weight than by volume. The volumetric measurement of liquids has other sources of inaccuracy. The shape of the target container, the viewing angle of the user, and the surface tension of the liquid can easily cause a 20% variation when visually judging what is “full” for small amounts of liquid. Weighing ingredients is the most reliable and consistent form of measuring, and it is the preferred method when it comes to using culinary ratios.
The standard digital scale can measure in metric or imperial units (also referred to as the U.S. customary units or avoirdupois units). A scale measuring a liquid detects weight, but some are configured to report the amount detected in volume units such as milliliters or fluid ounces (defined as 1/16 of a pint or 1/128 of a gallon in the US customary units system). However, this assumes the liquid is water or has a similar volume/weight ratio (density) as water. Some liquids have densities that are different from water, which can throw off the accuracy of using a scale to determine volume. For example, one milliliter is one gram of water and 30 grams of water is approximately 1 fluid ounce. The specific gravity of water is 1.00 (specific gravity is the ratio of density of fluid in question to the density of water). The specific gravity of simple syrup is typically 1.33. If a recipe calls for a 1 fluid ounce of simple syrup, weighing out one ounce of simple syrup will be rather inaccurate unless the scale knows the specific gravity of the fluid it is weighing and calculates fluid ounces accordingly.
Using a scale to maintain ratios can be especially challenging for standard cocktail recipes, which typically specify volume measurements. As an example a classic margarita recipe calls for the following ingredients:
60 ml tequila(2 fluid oz.)30 ml Cointreau(1 fluid oz.)23 ml fresh Lime Juice( 3/4  fluid oz.)The specific gravity for each ingredient is approximately:
Tequila(0.95)Cointreau(1.04)Lime Juice(1.4)To measure a correct ratio by weight, the specific gravity of each ingredient must be considered. A scale assuming the specific gravity of water to measure ingredients would yield:
60 grams tequila =68.01 ml = (2.3 fluid oz)30 grams Contreau =29.0 ml =(0.98 fluid oz)23 grams fresh lime juice =13.6 ml =(0.46 fluid oz)This would result in significantly different ratios of ingredients than the original recipe and would not taste the same. A correct measurement incorporating the specific gravity of each ingredient would measure the following:
57 grams Tequila =(2 fluid oz.)31.2 grams Cointreau =(1 fluid oz.)32.2 grams Lime Juice =( 3/4  fluid oz.)
The standard digital kitchen scale typically has a “tare” button. This is used to subtract the current weight on the smart scale 102, setting the current measured weight to zero. Using this button allows the weight of a containing vessel (like a bowl or glass) to be eliminated when measuring an ingredient. Using this button sequentially to build a multi-step recipe allows each ingredient to be measured independently as it is added.
This is a useful system and minimizes the use of containers. However, it does not have any awareness of the ingredients being measured or specific actions of the recipe. What if you make a mistake reading a recipe? Let's say a recipe asks for 70 grams of grape juice and 100 grams of apple juice and the user puts them in backwards (70 grams of apple juice and 100 grams of grape juice). It can be difficult to fix this, especially in the context of the entire recipe, where the measured amount for each ingredient must now be precisely altered to maintain a proper ratio.
Another problem is scaling a recipe. Simple scaling is practicable in one's head when doubling (2×) or halving (½) the recipe. However, other scaling changes, like making 30% less, or 1.75 times more, become more complicated. The common digital kitchen scale offers no assistance here.